In such a plasma display device or a liquid crystal display, an image is displayed on scanning lines sequentially as a line of pixels located on each scanning line.
In order to improve quality of the image displayed on the scanning lines, interpolation pixels are generated on each interpolation scanning line produced between two adjoining scanning lines.
For example, as a circuit which generates interpolation pixels, Japanese Laid-Open Patent Publication No. 2003-230109 discloses a circuit which detects a direction where correlation of pixel values is the highest from pixels on adjoining scanning lines, and generates a pixel value of the interpolation pixel by calculating the average of pixel values of the pixels of the detected direction.
However, when calculating the average of the pixel values of the above pixels with the highest correlation, differences of pixel values between the interpolation pixel and each pixel which adjoin the interpolation pixel may become large, and the interpolation pixel may cause a noise problem.
For example, when pixels having the highest correlation are high luminance, the generated interpolation pixel is also high luminance. So, if all other surrounding pixels are low luminance, the height of luminance of the interpolation pixel is conspicuous as a noise.